Successful short-term suppression of clarithromycin-resistant Mycobacterium avium complex bacteremia in AIDS

During a randomized study of clarithromycin plus clofazimine with or withou t ethambutol in patients with AIDS and Mycobacterium avium complex (MAC) ba cteremia, eight participants received additional antimycobacterial drugs fo llowing the detection of a clarithromycin-resistant isolate (MIC, >8 mu g/m L). A macrolide (seven received clarithromycin, one azithromycin) and clofa zimine were continued; additional treatment included various combinations o f ethambutol, ciprofloxacin, amikacin, and rifabutin. After the detection o f a resistant isolate and before receipt of additional antimycobacterials, the median peak MAC colony count in blood was 105 cfu/ml (range, 8-81,500 c fu/ml), After additional antimycobacterials, the median nadir MAC colony co unt was 5 cfu/ml (range, 0-110 cfu/ml). Five (63%) of eight patients had a greater than or equal to 1 log(10) decrease, including two who achieved neg ative blood cultures; all of these responses occurred in patients originall y assigned to clarithromycin plus clofazimine. Treatment of clarithromycin- resistant MAC bacteremia that emerges during clarithromycin-based treatment can decrease levels of bacteremia and transiently sterilize blood cultures .